N-I

The N-I rocket[1]
Function	Small-lift launch vehicle
Manufacturer	McDonnell Douglas (design) Mitsubishi Heavy Industries (production)
Country of origin	United States (design) Japan (production)
Size
Height	34 m (112 ft)[1]
Diameter	2.44 m (8.0 ft)
Mass	131,330 kg (289,530 lb)[1]
Stages	2 or 3
Capacity
Payload toLEO
Mass	1,200 kg (2,600 lb)[1]
Payload toGTO
Mass	360 kg (790 lb)[1]
Associated rockets
Family	Delta
Derivative work	N-II
Launch history
Status	Retired
Launch sites	Tanegashima,Osaki
Total launches	7
Success(es)	6
Partial failure	1
First flight	9 September 1975
Last flight	3 September 1982
Boosters –Castor 2
No. boosters	3[2]
Maximum thrust	258.9 kN (58,200 lbf) each
Total thrust	776.7 kN (174,600 lbf)
Specific impulse	262 s (2.57 km/s)
Burn time	37 seconds
Propellant	Solid
First stage –Thor-ELT
Powered by	1 × MB-3-3
Maximum thrust	866.7 kN (194,800 lbf)
Specific impulse	290 s (2.8 km/s)
Burn time	270 seconds
Propellant	RP-1 / LOX
Second stage
Powered by	1 × LE-3
Maximum thrust	52.9 kN (11,900 lbf)
Specific impulse	290 s (2.8 km/s)
Burn time	246 seconds
Propellant	N2O4 / A-50
Third stage (optional) –Star-37N
Maximum thrust	45 kN (10,000 lbf)
Specific impulse	290 s (2.8 km/s)
Burn time	42 seconds
Propellant	Solid
[edit on Wikidata]

TheN-I orN-1 was a derivative of the AmericanThor-Delta rocket, produced under license in Japan. The N stood for "Nippon" (Japan). It used aLong Tank Thor first stage, aMitsubishi Heavy Industries-designedLE-3 engine on the second stage,^[3][4][5] and threeCastor SRMs.^[2][6] Seven were launched between 1975 and 1982, before it was replaced by theN-II. Six of the seven launches were successful, however on the fifth flight, there was recontact between the satellite and the third stage, which caused the satellite to fail.

On 29 February 1976, the second N-I conducted the only orbital launch, as of February 2024, to occur on aleap day.^[7]

ETS-1 was the first satellite launched by theNASDA. It had the objective of acquiring information on N-series launch vehicles, orbit injection, and tracking and control.^[10] It ceased operations on 28 April 1982.

UME was Japan's first Ionosphere Sounding Satellite.^[11] It was used to monitor radio waves in the ionosphere and forecast conditions for shortwave communications. A power supply issue caused Ume to stop functioning one month after launch.^[15]

KIKU-2 was NASDA's first satellite launched to GEO.^[12] It was intended to gather data on geostationary satellite launch, tracking, control, orbit maintenance, and attitude control as well as carrying out experiments on communications equipment. KIKU-2 ceased operations on 10 December 1990, leaving GEO.

UME-2 had similar goals to the original UME satellite, but was much more successful in carrying them out. While it was originally intended to gather data for only a year and a half, UME-2 ceased operations on 23 February 1983.

Both ECS satellites were unsuccessful in completing their mission. During the first ECS launch, the third stage rocket collided with the satellite shortly after separation. During the ECS-2 launch, the satellite stopped transmitting shortly after separation. The satellites had the intention of conducting millimeter wave experiments. The JAXA website states that "we learned some valuable lessons on satellite separation technology and apogee engine from this experience".^[13]

KIKU-4 was developed to acquire data on designing earth observation satellites with high power requirements.^[14] KIKU-4 completed testing of three-axis attitude control, deployable solar panels, movable heat control, and ion engine operation. On 8 April 1985, the satellite ran out of fuel and ceased operation.

• Comparison of orbital launchers families
• Delta rocket
• H-I
• H-II
• H-IIA
• N-II (rocket)
• PGM-17 Thor

• Mitsubishi Heavy Industries space launch vehicles
• Thor (rocket family)
• Vehicles introduced in 1975
• Japan–United States relations

• Articles with short description
• Short description is different from Wikidata
• Use dmy dates from October 2020